Telephone system



July 23, 1940.

E. JAUCH 2,209,622

TELEPHONE SYSTEM Filed Nov. 13, 1937 1 l a o g n B l l l I Q N E INVENTOR.

EUGEN JAUCH ATTORNEY. I

Patented July 23, 1940 s. PATENT OFFICE v 1' TELEPHONE SYSTEM Eugen Jauch, Berlin siemensstadt, Germany, as-

signor to Siemens 8 Halske Aktiengesellschaft, Wernerwerk, Siemensstadt, near Berlin, Germany Application November 13, 1937, Serial No. 174,328

g In Germany December 17, 1936 6 Claims.

1 ration of the switches at the branch stations on the termination of a call is brought about by transmitting resetting impulses from the central station.

Arrangements are known in which the switches at the branch stations of party lines are in. fiuencedon the termination of a call by restoring devices in the central station until a testing device hasestablished a the fact that all switches have been restored to normal. These arrangements have the disadvantage that for example in the case of a switch Jamming resetting impulses, are permanently transmitted from the central station. over the line whereby the line is blocked.= t

Itis also known to provide a time switching device in the central station of a party line which switching device connects resetting current to the party line for-a predetermined time. This arrangement. has the, disadvantage that with normal restoration 01117116.. stepping switches an unnecessarily large number of impulses aretransmitted and the connecting line cannot be released except after the expiration of a given time.

- The invention aims ontthe. other hand at avoiding the permanent transmission of resetting im pulses in the event of a switch jamming in the branchstation and'the consequent permanent seizure of a party line and on the other hand at avoiding the transmission of unnecessary impulses when all switches have been restored to normal. 2 a

. This is achieved by the invention in that when the factis established that a switch has not been restoredxto .normal a time switching device is influenced by the testing device and independent1y1of the restoration of all the switches to normal prevents further transmission of resetting impulses and releases, the party. line.

. Conveniently signalling devices are operated in the exchange on the operation of the time switching device. During theprogress of afresh call the signals are disconnectedbut are again operated if the fault-remains uncleared after the termination of the call.

i The invention .willbe described in greaterdetail with reference to the drawing. V

The invention .is, however, not limited to the arrangements shown inthe drawing. Only the details ofthe circuitwhich arenecessary for the understanding of the invention are shown.

In the drawing a plurality of branch stations TI and T2 are connected to the party line V'L. The connection of the party line VL to the individual branch stations takes place over stepping switches Wrl and Wr2 etc., disposed at each 5' branch station. The stepping switches at each branch station are connected to the a-lead of the connecting line both in the normal position and in a particular position which corresponds to the number of the branch station in question.

The establishment of a call does not concern the invention. It will only be mentioned that on the removal of the receiver at a branch station for the purpose of establishing an outgoing call earth potential is applied to the. LL-lead whereby the startingrelay X in the exchange or control station VSt becomes energized. Relay X applies alternating current to the b-lead in the exchange and thereby causes all the relays 0 in the branch stations to energize. The 0 relays connect the stepping magnets Wr of the stepping switches to the. b-leadwhereupon these switches and the discriminator switch Da are advanced SYIIChI'O'. nously until a stepping switch has reached the. calling stations contact. 25

The switching operations take place in a corresponding manner in the case ofincoming calls.

The invention is concerned only with the resto ration of all the stepping switches to normal.

So long as a call isin progress the discriminator Da and the switches Wr at the branch sta tions are away from the normal position so that relay A is energized over wiper 11:12, and the a-lead of the connecting line V'L and the wiper wr at a station engaged in a call. When the subscribers replace their receivers the energizing cir-' cuit for relay A passing over the a-lead is broken; Relay A releases in consequence andconnects an interrupter U to the b-lead of the connecting line over its contact l5a and at the same time at 40 contacts l'la completes the stepping circuit for the rotary magnet Da of the common'discriminator. Relay V is energized through the release of relay A and breaks the 'c-lead of the connecting line to the exchange at contact 2411 and disconnects the common starting relay X at its contact 2522. The stepping magnets Wrl, Wr2, etc., at all the branch stations and in addition the rotary magnet Da of the common switch are now influenced by the impulse sender U, the stepping magnets over earth, battery, impulse senderU, contact 15a, wiper 11113 of the contact switch, the b-lead of the connecting line VL, wiper wrl of the stepping switch at station Tl, magnet WM and earth (and correspondingly for W12 etc.) 5

J contact 97' looks relay K in a 'loc'kingcircuit.

and the rotary magnet Da over earth, battery, impulse sender U, wiper dad of the discriminator switch, contact Ila, rotary magnet Da and earth.

The transmission of the re-setting impulses over the b-lead continues until the discriminator Da reaches its rest position when the stepping circuit is brokenat wiper da3. At this moment switches at the branch station will also be in the rest position if they have been advanced in synchronism with the discriminator switch Do.

If it should now happen that one or more of the switches for example that at station Tl should not have been restored to normal on account of the fault the following cir'c'uit'is set up for the testing relay K in the exchange'z earth, battery, relay K, contact 99, the zero position of wiper dal in the common discriminator, the b-leadpwiper wrl away from the zero position of-the' switch Wrl at the branch station TI the stepping magnetWrl and earth. Relay K energizes in this circuit. At the same time the switch Wrl, provided that it is not mechanicallylocked, is ad- Vanced one step. Through the closing of contact I lie, the relay G is energized over earth, contacts li'lc, and 123;, relay G, battery and earth. Through the closing of contact 13g, relay J is en er'gized over earth, contacts llk and I39, relay J, batteryand earth. Relay J opens contact 97 and thereby breaks the stepping magnet WM and at In addition relay G is 'deenergized through the opening-of contact I27 so that relay J is released through the opening of contact Hg and again connects relay K to the lJ-lead at contact 97'. If afterthis step the switch Wrl is still away from the normal position the stepping magnet WM ofthe switch Wrl against operates over the circ'juit: earth, battery, relay K, contact 99', the zero position of the switch, wiper Dal, the b -lead, wiper'jurrl, magnet Wrl andearth. If on the other hand the switch Wrl has reached the rest position no further energizing of thestepping magnet Wrl takes place since the stepping circult is broken in the rest position of the switch.

The switching operations would proceed in a similar way if further switches were away from the normal position.

In order to avoid a permanent transmission of resetting impulses and thus a permanent seizure or the party line in the event'of one of the switches sticking, relay K switches on a time switching device, for example the thermo-relay Th, at contact 2670 when relay K energizes. Since relay K holds up during the transmission of resetting impulses in the stepping circuit over the b -lead, and, when relay J energizes, over the op erated contact 97', andearth, the thermo-relay Th is connected to battery until relay K is disconnected. Relay, V is held energized over contact 23k and on the termination of the connection is connected in a circuit passing over wiper rich but is disconnected again when the wiper do reaches the rest position. ,In the time between the breaking of this circuit and the connection by relay K the relay V holds up on account of its slow-to-release feature. Through the energizing of relay V the party line is guarded as regards both incoming and outgoing calls until relay K is disconnected.

i If, for example, as a result of the switch Wrl sticking relay K'does not release then after a given time which normally suflices' to bring the switches at the'branch stations to the normal position the thermo-contact th of the thermorelay' Th becomes operative and connects relay S to battery. Relay S energizes and connects an alarm device AL (for example a lamp) over contact 2 I s and holds up over resistance W2, contact 22s, the zero position of wiper dal, lead b, wiper w rl, stepping magnet Wrl and earth. Through the switching over of contact 225 relay K releases and at contact 2310 disconnects relay V. Contact 241] completes the c-lead of the connecting line VL and contact 2512 the starting lead, in preparation. The party line is thus free again for seizure both in the outgoing and incoming directions independently of the existence of a fault, for example at station TI. The other branch stations on the party line are thus no longer prejudiced by a fault at any one branch station. The system is moreover so arranged that a fault remains signalled over relay S until cleared. When a new call is initiated the signalling is transitor- ,ily removed during the new call and reoperated again when this call is released in that relays K, Th, and S again energize and efiect signalling'fon account of the maintenance of the fault, the example at switch Wrl, as described until the fault is removed by the supervisory operator. A Although in the arrangement described the switches at the branch stations are influenced over one lead and earth the-invention is not limited to this particular embodiment. The switches can, for example, be arranged in bridge across the two leads of the common connecting line in the known way in which case the setting of the switches takes place by impulses in one direction and the testing for establishing the calling party by current in the opposite direction.

What is claimed is: 1. In a telephone system, a party line having a plurality of stations, a device at each station operated during the extension of a call for connecting one of the stations to the line, means for resetting said devices to normal on termination of a call, testing means operated when any of said devices fail to return to normal, means operated responsive thereto for causing the return of such devices to normal, and other means controlled by said testing means for rendering said last means ineffective after a predetermined time. I 2. In a telephone system as claimed in claim 1, wherein said means operated responsive to the operation of the testing means causes the testing means to control the return of such devices to normal. 3. In a telephone system, a party line having. a plurality of stations, a selector at each station operated during the extension of a call for connecting one of the stations to the line, means for resetting said selectors to normal on termination of a call, a device including a test relay operated thereafter when a selector fails to return to normal for causing the return to normal of such a selector, a delay device energized responsive to the operation of said relay for rendering said first device ineffective after a predetermined time; and signalling means operated responsive to the operation of said delay device when a selector has not been restored to normal.

4. In an automatic circuit arrangement, a control station, a line extending therefrom, a plurality of branch stations associated with the line, a device at each station, means for operating the devices at said branch stations to connect one of the branch stations to the line, means operated to return all of said devices at the branch stations to normal under control of the device at said control station, testing means operatedwhen any of the branch station devices fail to return to normal, means operated responsive to the operation of said testing means for causing said branch station device to be returned to normal, and other means operated by saidtesting means for cone trolling the last means.

5. In an automatic circuit arrangement, a plurality of branch stations, aline comprising two conductors associated therewith, a connecting device at each station, means for causing the transmission of a series of impulses over one of the conductors, said devices responding simultaneous- 1y to said impulses for connecting one of the stations to the line, means for causing the transmission of another series of impulses over said one conductor for causing the return of said devices to normal, a testing, relay operated thereafter over said one conductor when any of said devices fail to return to normal, means operated responsive thereto for transmitting a difierent series of impulses over said one conductor to return such devices to normal, and means controlled by the operation of said testing relay for releasing said line by rendering said last means ineffective after a given time.

6. In an automatic circuit arrangement, as claimed in claim 5, control means at each station, said means effective over the other of said conductors for controlling said first and second means.

EUGEN JAUCH. 

